JPWO2019112017A1 - Manufacturing method of powder, powder coating and laminate - Google Patents

Abstract

Provided is a method for producing a laminate using a powder capable of easily forming a fluororesin layer having a smooth surface and a powder coating material containing the powder. The powder of the present invention is a powder composed of resin particles containing a fluoropolymer having a unit based on tetrafluoroethylene and having a melting point of 260 to 320 ° C., where D50 is X and D10 is Y. , Y / X is 0.3 or less. Further, it is preferable that D10 is 4 μm or less and D50 is 15 to 60 μm.

Description

The present invention relates to a method for producing a powder containing fine particles, a powder coating material, and a laminate.

Fluoropolymers such as copolymers (PFA) having units based on tetrafluoroethylene and units based on perfluoro (alkyl vinyl ether) have a low coefficient of friction and are excellent in properties such as non-adhesiveness, chemical resistance, and heat resistance. .. Therefore, fluoropolymers are widely used for surface processing of food industry products, kitchen utensils such as frying pans and pots, household products such as irons, electrical industry products, and machinery industry products.

Patent Document 1 discloses a method in which a powder coating material containing a powder composed of fluoropolymer particles is coated on a substrate and fired to form a fluororesin layer to obtain a laminate. Patent Document 2 discloses a powder composed of fluoropolymer particles having a functional group such as a carbonyl group-containing group as a powder having excellent adhesiveness to a base material.

International Publication No. 2011/048965 International Publication No. 2016/017801

However, if the particle size of the resin particles constituting the powder is not adjusted, the surface of the formed fluororesin layer tends to have irregularities. In particular, the present inventors have found that such a phenomenon becomes remarkable when a powder made of resin particles containing a high melting point fluoropolymer is fired to form a fluororesin layer.
An object of the present invention is to provide a powder capable of easily forming a fluororesin layer having a smooth surface, a powder coating material containing such powder, and a method for producing a laminate using such powder coating material.

The present invention has the following aspects.
<1> A powder composed of resin particles containing a fluoropolymer having a unit based on tetrafluoroethylene and having a melting point of 260 to 320 ° C.
A powder having a Y / X of 0.3 or less, where X is a volume-based cumulative 50% diameter and Y is a volume-based cumulative 10% diameter.
<2> The powder of <1> having a volume-based cumulative 10% diameter of 4 μm or less and a volume-based cumulative 50% diameter of 15 to 60 μm.
<3> When the amount of resin particles having a particle size of 4 μm or less contained in the powder is A and the amount of resin particles having a particle size of 15 to 60 μm is B, the A / B is 0.1 or more. There is a powder of <2>.
<4> The powder of <2> or <3>, wherein the amount of the resin particles having a particle diameter of 4 μm or less contained in the powder is 5 to 25% by volume.
<5> Any powder of <1> to <4> having a volume-based cumulative 100% diameter of 220 μm or less.
<6> The powder according to any one of <1> to <5>, wherein the fluoropolymer has at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group and an isocyanate group.
<7> The powder of <6>, wherein the fluoropolymer has a unit based on the tetrafluoroethylene and a unit having the functional group.
<8> A powder coating material containing any of the powders <1> to <7>.
<9> The powder coating material of <8>, wherein the amount of the powder contained in the powder coating material is 90 to 100% by mass.
<10> A method for producing a laminate having a base material and a fluororesin layer provided on the base material and formed from any of the powders <1> to <7>.
A method for producing a laminate, wherein a powder coating material containing the powder is supplied onto the base material and fired to obtain the fluororesin layer.
<11> The production method of <10>, wherein the powder coating material is fired by heating it to a temperature equal to or higher than the melting point of the fluoropolymer.
<12> The method for producing <10> or <11>, wherein the fluororesin layer has a thickness of 50 to 750 μm.

According to the present invention, a fluororesin layer having a smooth surface can be easily formed.

It is a figure for demonstrating the state change at the time of forming a fluororesin layer using the powder of this invention. It is a figure for demonstrating the state change at the time of forming a fluororesin layer using the conventional powder.

The definitions of the following terms apply throughout the specification and claims.
The "heat-meltable polymer" means a polymer in which an MFR of 0.01 to 1000 g / 10 minutes exists at a temperature higher than the melting point of the polymer by 20 ° C. or more under a load of 49 N.
“Polymer melting point” means the temperature corresponding to the maximum melting peak of the polymer as measured by differential scanning calorimetry (DSC).
"Polymer MFR" is a melt mass flow rate specified in JIS K 7210-1: 2014 (corresponding international standard ISO 1133: 1: 2011).
"Volume-based cumulative 50% diameter of powder (D50)" measures the particle size distribution of powder by laser diffraction / scattering method, obtains a cumulative curve with the total volume of powder as 100%, and is on the cumulative curve. The particle size at the point where the cumulative volume is 50%.
Similarly, "volume-based cumulative 10% diameter of powder (D10)", "volume-based cumulative 90% diameter of powder (D90)" and "volume-based cumulative 100% diameter of powder (D100)" are volumes. The standard cumulative 10% diameter, the volume standard cumulative 90% diameter, and the volume standard cumulative 100% diameter (maximum particle diameter).
That is, the powders D10, D50, D90 and D100 have a volume-based cumulative 10% diameter, a volume-based cumulative 50% diameter, a volume-based cumulative 90% diameter and a volume-based cumulative 100% diameter of the particles constituting the powder. ..
The "monomer-based unit" is a general term for an atomic group directly formed by polymerizing one molecule of a monomer and an atomic group obtained by chemically converting a part of the atomic group. In the present specification, a unit based on a monomer is also simply referred to as a "unit".
"(Meta) acrylate" is a general term for acrylate and methacrylate. Similarly, "(meth) acrylic acid" is a general term for acrylic acid and methacrylic acid, and "(meth) acryloyloxy group" is a general term for acryloyloxy group and methacryloyloxy group.

The resin particles constituting the powder of the present invention have a unit based on tetrafluoroethylene (hereinafter, also referred to as "TFE unit") and have a melting point of 260 to 320 ° C. (hereinafter, "F polymer"). Also referred to as).
The amount of the F polymer contained in the resin particles is preferably 80% by mass or more, more preferably 85% by mass or more, further preferably 90% by mass or more, and particularly preferably 100% by mass. When a powder composed of resin particles containing an F polymer is used in such an amount, the non-adhesiveness, chemical resistance, and heat resistance of the formed fluororesin layer (hereinafter, also referred to as “F resin layer”) are improved. Two or more kinds of F polymers may be used in combination.
Examples of other polymers include fluoropolymers other than F polymers, aromatic polyesters, polyamideimides, and thermoplastic polyimides. Two or more kinds of other polymers may be used in combination.

Examples of the F polymer include tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, and the like. Modified polytetrafluoroethylene, a polymer in which at least one functional group (hereinafter, also referred to as “adhesive group”) selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group and an isocyanate group has been introduced into these. Can be mentioned. Polytetrafluoroethylene can also be used as the F polymer as long as it exhibits thermal meltability.

The modified polytetrafluoroethylene, (i) tetrafluoroethylene (hereinafter also referred to as "TFE".) And a trace amount of _{CH 2 = CH (CF 2)} 4 copolymers of F, of (ii) (i) above Copolymers of copolymers and monomers having a trace amount of adhesive groups (hereinafter, also referred to as "adhesive monomers"), (iii) copolymers of TFE and trace amounts of adhesive monomers, (iv) plasma treatment. Examples thereof include polytetrafluoroethylene in which an adhesive group has been introduced by (v) plasma treatment and the like, and the copolymer (i) in which an adhesive group has been introduced by plasma treatment or the like.

The melting point of the F polymer is 260 to 320 ° C., preferably 280 to 320 ° C., more preferably 295 to 315 ° C., still more preferably 295 to 310 ° C. When the melting point of the F polymer is at least the above lower limit value, the heat resistance of the F resin layer is enhanced. When the melting point of the F polymer is not more than the above upper limit value, the thermal meltability of the F polymer is improved.
The melting point of the F polymer can be adjusted by the type and ratio of the units constituting the F polymer, the molecular weight of the F polymer, and the like. For example, as the proportion of TFE units increases, the melting point of the F polymer tends to rise.

The MFR at a temperature 20 ° C. or higher higher than the melting point of the F polymer is preferably 0.1 to 1000 g / 10 minutes, more preferably 0.5 to 100 g / 10 minutes, further preferably 1 to 30 g / 10 minutes, and 5 to 5 20 g / 10 minutes is particularly preferable. When the MFR is at least the above lower limit value, the thermal meltability of the F polymer is further improved, and the appearance of the F resin layer is improved. When the MFR is not more than the above upper limit value, the mechanical strength of the F resin layer is increased.
The MFR is a measure of the molecular weight of the F polymer, and a large MFR indicates a small molecular weight, and a small MFR indicates a large molecular weight. The MFR of the F polymer can be adjusted according to the manufacturing conditions of the F polymer. For example, if the polymerization time is shortened during the polymerization of the monomer, the MFR of the F polymer tends to increase.

As the adhesive group, a carbonyl group-containing group is preferable from the viewpoint of excellent adhesiveness between the F resin layer and the base material or the like.
Examples of the carbonyl group-containing group include a hydrocarbon group having a carbonyl group between carbon atoms, a carbonate group, a carboxy group, a haloformyl group, an alkoxycarbonyl group, and an acid anhydride residue (-C (O) -OC (O)). -), Polyfluoroalkoxycarbonyl group, fatty acid residue.
As the carbonyl group-containing group, a hydrocarbon group having a carbonyl group between carbon atoms, a carbonate group, a carboxy group, a haloformyl group, an alkoxycarbonyl group and an acid can be used because the adhesiveness between the F resin layer and the base material is further excellent. An anhydride residues are preferred, and carboxy groups and acid anhydride residues are more preferred.
Examples of the hydrocarbon group in the hydrocarbon group having a carbonyl group between carbon atoms include an alkylene group having 2 to 8 carbon atoms. The carbon number of the alkylene group does not include the number of carbons constituting the carbonyl group.
Examples of the haloformyl group include -C (= O) -F and -C (= O) Cl.
Examples of the alkoxy group in the alkoxycarbonyl group include a methoxy group and an ethoxy group.

The adhesive group may be contained in the F polymer as an adhesive unit, or may be contained as an end group at the end of the main chain of the F polymer. When an adhesive group is contained as a terminal group of the main chain, the F polymer may or may not contain an adhesive unit.
The F polymer preferably contains a TFE unit and a unit based on an adhesive monomer (adhesive unit).
The adhesive group of the adhesive monomer may be one or two or more. When having two or more adhesive groups, the two or more adhesive groups may be the same or different.

Examples of the adhesive monomer include a monomer having a carbonyl group-containing group, a monomer having a hydroxy group, a monomer having an epoxy group, and a monomer having an isocyanate group. As the adhesive monomer, a monomer having a carbonyl group-containing group is preferable from the viewpoint of excellent adhesiveness between the F resin layer and the base material or the like.
Examples of the monomer having a carbonyl group-containing group include a cyclic monomer having an acid anhydride residue, a monomer having a carboxy group, a vinyl ester, a (meth) acrylate, and CF ₂ = CFOR ^f1 CO ₂ X ¹ (where R ^f1 is It is a perfluoroalkylene group having 1 to 10 carbon atoms or a perfluoroalkylene group having 2 to 10 carbon atoms having an etheric oxygen atom between carbon atoms, and X ¹ is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. .) Can be mentioned.

Cyclic monomers having an acid anhydride residue include unsaturated dicarboxylic acid anhydrides. Examples of the unsaturated dicarboxylic acid anhydride include itaconic anhydride (hereinafter, also referred to as “IAH”), citraconic anhydride (hereinafter, also referred to as “CAH”), and 5-norbornene-2,3-dicarboxylic acid anhydride (hereinafter, also referred to as “CAH”). Also known as: hymicic anhydride; hereinafter also referred to as "NAH"), maleic anhydride.
Examples of the monomer having a carboxy group include unsaturated dicarboxylic acids (itaconic acid, citraconic acid, 5-norbornene-2,3-dicarboxylic acid, maleic acid, etc.) and unsaturated monocarboxylic acids (acrylic acid, methacrylic acid, etc.). Be done.
Examples of the vinyl ester include vinyl acetate, chloroacetic acid vinyl, vinyl butanoate, vinyl pivalate, vinyl benzoate, and vinyl crotonic acid.
Examples of the (meth) acrylate include (polyfluoroalkyl) acrylate and (polyfluoroalkyl) methacrylate.

As the monomer having a carbonyl group-containing group, a cyclic monomer having an acid anhydride residue is preferable, and IAH, CAH or NAH is more preferable, from the viewpoint of further improving the adhesiveness between the F resin layer and the substrate and the like. Using IAH, CAH or NAH facilitates the production of F-polymers with acid anhydride residues. As the monomer having a carbonyl group-containing group, NAH is particularly preferable because the adhesiveness of the F resin layer is likely to increase.

Examples of the monomer having a hydroxy group include a vinyl ester having a hydroxy group, a vinyl ether having a hydroxy group, an allyl ether having a hydroxy group, a (meth) acrylate having a hydroxy group, hydroxyethyl crotonate, and allyl alcohol.
Examples of the monomer having an epoxy group include unsaturated glycidyl ether (allyl glycidyl ether, 2-methylallyl glycidyl ether, vinyl glycidyl ether, etc.) and unsaturated glycidyl ester (glycidyl (meth) acrylate, etc.).
Examples of the monomer having an isocyanate group include 2- (meth) acryloyloxyethyl isocyanate, 2- (2- (meth) acryloyloxyethoxy) ethyl isocyanate, and 1,1-bis ((meth) acryloyloxymethyl) ethyl isocyanate. Be done.
Two or more kinds of adhesive monomers may be used in combination.

Units other than the adhesive unit and the TFE unit include a unit based on perfluoro (alkyl vinyl ether) (hereinafter, also referred to as "PAVE") (hereinafter, also referred to as "PAVE unit"), and hexafluoropropylene (hereinafter, also referred to as "PAVE unit"). Units based on (also referred to as "HFP") (hereinafter, also referred to as "HFP unit"), adhesive monomers, units based on TFE, PAVE and other monomers other than HFP can be mentioned.

As PAVE, CF ₂ = CFOCF ₃ , CF ₂ = CFOCF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₃ (hereinafter, also referred to as “PPVE”), CF ₂ = CFOCF ₂ CF ₂ CF ₂ CF ₃ , CF ₂ = CFO (CF ₂ ) ₈ F is mentioned, and PPVE is preferable.
Two or more types of PAVE may be used in combination.

Examples of other monomers include other fluorine-containing monomers (excluding adhesive monomers, TFE, PAVE and HFP) and other non-fluorine-containing monomers (excluding adhesive monomers).
Other fluorine-containing monomers include vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, CF ₂ = CFOR ^f3 SO ₂ X ³ (however, R ^f3 is a perfluoroalkylene group having 1 to 10 carbon atoms. or a perfluoroalkylene group having 2 to 10 carbon atoms having an etheric oxygen atom between carbon atoms, ^{X 3} is a halogen atom or a hydroxy _{group.), CF 2 = CF (} CF 2) p OCF = CF 2 (However, p is 1 or 2.), CH ₂ = CX ⁴ (CF ₂ ) _q X ⁵ (where X ⁴ is a hydrogen atom or a fluorine atom, q is an integer of 2 to 10 and X. ⁵ is a hydrogen atom or a fluorine atom), perfluoro (2-methylene-4-methyl-1,3-dioxolane), and examples thereof. Two or more kinds of other fluorine-containing monomers may be used in combination.
CH ₂ = CX ⁴ (CF ₂ ) _q X ⁵ includes CH ₂ = CH (CF ₂ ) ₂ F, CH ₂ = CH (CF ₂ ) ₃ F, CH ₂ = CH (CF ₂ ) ₄ F, CH ₂ = CF (CF ₂ ) ₃ H, CH ₂ = CF (CF ₂ ) ₄ H, and CH ₂ = CH (CF ₂ ) ₄ F, CH ₂ = CH (CF ₂ ) ₂ F are preferable.

Examples of other non-fluorine-containing monomers include ethylene and propylene, and ethylene is preferable. Two or more kinds of other non-fluorine-containing monomers may be used in combination.
As the other monomer, another fluorine-containing monomer and another non-fluorine-containing monomer may be used in combination.

When the F polymer has an adhesive group as a terminal group at the end of the main chain, the adhesive group is preferably an alkoxycarbonyl group, a carbonate group, a carboxy group, a fluoroformyl group, an acid anhydride residue, or a hydroxy group. The adhesive group can be introduced by appropriately selecting a radical polymerization initiator, a chain transfer agent, or the like used in the production of the F polymer.

As the F polymer, a copolymer having an adhesive unit, a TFE unit and a PAVE unit (hereinafter, also referred to as a copolymer (A1)), an adhesive unit, a TFE unit and an HFP unit are used from the viewpoint of increasing the heat resistance of the F resin layer. A copolymer having the above (hereinafter, also referred to as a copolymer (A2)) is preferable, and a copolymer (A1) is more preferable.

The copolymer (A1) may have at least one of the HFP unit and the other unit, if desired. That is, the copolymer (A1) may be a copolymer having an adhesive unit, a TFE unit and a PAVE unit, a copolymer having an adhesive unit, a TFE unit, a PAVE unit and an HFP unit, and the adhesive unit and the TFE unit. It may be a copolymer having a PAVE unit and another unit, or a copolymer having an adhesive unit, a TFE unit, a PAVE unit, an HFP unit and another unit.
As the copolymer (A1), a copolymer having a monomer-based unit having a carbonyl group-containing group, a TFE unit, and a PAVE unit is preferable, and an acid anhydride is preferable, from the viewpoint of further enhancing the adhesiveness between the F resin layer and the base material. A copolymer having a unit based on a cyclic monomer having a residue, a TFE unit, and a PAVE unit is more preferable.
Preferred specific examples of the copolymer (A1) include a copolymer having TFE units, PPVE units and NAH units, a copolymer having TFE units, PPVE units and IAH units, and a copolymer having TFE units, PPVE units and CAH units. Can be mentioned.
The ratio of the adhesive units in the copolymer (A1) is preferably 0.01 to 3 mol%, more preferably 0.05 to 1 mol%, out of all the units constituting the copolymer (A1). In this case, it is easy to balance the adhesiveness between the F resin layer and the base material, the heat resistance of the F resin layer, and the color.
The proportion of TFE units in the copolymer (A1) is preferably 90 to 99.89 mol%, more preferably 96 to 98.95 mol%, of all the units constituting the copolymer (A1). In this case, it is easy to balance the heat resistance, chemical resistance, etc. of the F resin layer with the heat meltability, stress crack resistance, etc. of the copolymer (A1).
The ratio of PAVE units in the copolymer (A1) is preferably 0.1 to 9.99 mol%, more preferably 1 to 9.95 mol%, out of all the units constituting the copolymer (A1). In this case, it is easy to adjust the thermal meltability of the fluorine copolymer (A1).
The total of the adhesive unit, the TFE unit and the PAVE unit in the copolymer (A1) is preferably 90 mol% or more, more preferably 98 mol% or more. The upper limit is 100 mol%.

The copolymer (A2) may have at least one of a PAVE unit and another monomer unit, if desired. That is, the copolymer (A2) may be a copolymer having an adhesive unit, a TFE unit and an HFP unit, a copolymer having an adhesive unit, a TFE unit, an HFP unit and a PAVE unit, and an adhesive unit and a TFE unit. It may be a copolymer having an HFP unit and another monomer unit, or a copolymer having an adhesive unit, a TFE unit, an HFP unit, a PAVE unit and another unit.
As the copolymer (A2), a copolymer having a monomer-based unit having a carbonyl group-containing group, a TFE unit, and an HFP unit is preferable, and an acid anhydride is preferable, from the viewpoint of further enhancing the adhesiveness between the F resin layer and the base material. Copolymers with units based on cyclic monomers with residues, TFE units and HFP units are more preferred.
Preferred specific examples of the copolymer (A2) include a copolymer having TFE units, HFP units and NAH units, a copolymer having TFE units, HFP units and IAH units, and a copolymer having TFE units, HFP units and CAH units. Can be mentioned.

The ratio of the adhesive units in the copolymer (A2) is preferably 0.01 to 3 mol%, more preferably 0.05 to 1.5 mol%, out of all the units constituting the copolymer (A2). In this case, it is easy to balance the adhesiveness between the F resin layer and the base material, the heat resistance of the F resin layer, and the color.
The proportion of TFE units in the copolymer (A2) is preferably 90 to 99.89 mol%, more preferably 92 to 96 mol%, of all the units constituting the copolymer (A2). In this case, it is easy to balance the heat resistance, chemical resistance, etc. of the F resin layer with the heat meltability, stress crack resistance, etc. of the copolymer (A2).
The proportion of HFP units in the copolymer (A2) is preferably 0.1 to 9.99 mol%, more preferably 2 to 8 mol%, of all the units constituting the copolymer (A2). When the ratio of HFP units is within the above range, the thermal meltability of the copolymer (A2) is further enhanced.
The total ratio of the adhesive unit, the TFE unit and the HFP unit in the copolymer (A2) is preferably 90 mol% or more, more preferably 98 mol% or more. The upper limit is 100 mol%.
The proportion of each unit in the F polymer is determined by NMR analysis such as molten nuclear magnetic resonance (NMR) analysis, fluorine content analysis, and infrared absorption spectrum analysis. For example, as described in JP-A-2007-314720, the ratio (mol%) of the adhesive unit to all the units constituting the F polymer can be obtained by using a method such as infrared absorption spectrum analysis.

Examples of the method for producing the F polymer include (i) a method of polymerizing an adhesive monomer and TFE with PAVE, FEP, and other monomers as needed, and (ii) a functional group that produces an adhesive group by thermal decomposition. A method of heating a fluorine-containing copolymer having a unit and a TFE unit to thermally decompose a functional group to form an adhesive group (for example, a carboxy group), (iii) an adhesive monomer to a fluorine-containing copolymer having a TFE unit. A method of graft-polymerizing the above is mentioned, and the method (i) above is preferable.
The polymerization method (lumpy polymerization method, solution polymerization method, suspension polymerization method, emulsion polymerization method, etc.) is not particularly limited and can be appropriately set. Further, the amount and type of the solvent, the polymerization initiator, and the chain transfer agent used in the polymerization can be appropriately set. In addition, the polymerization conditions (temperature, pressure, time, etc.) can be appropriately set according to the type of monomer used.

In the powder of the present invention, when D50 is X and D10 is Y, Y / X is 0.3 or less. That is, the powder of the present invention includes resin particles having a medium particle size (hereinafter, also referred to as "moderate particles") and resin particles having a sufficiently small particle size with respect to the medium particles (hereinafter, "fine particles"). Also referred to as "particles").
The F resin film is formed by supplying powder onto a base material to form a powder layer, and then firing the powder layer. At this time, as shown in FIG. 1A, voids are formed between the moderate particles in the powder layer, and the voids are filled with fine particles. Therefore, when the powder layer is fired, as shown by the thick line in FIG. 1 (b), the surface (moderate particles and fine particles) of the powder layer starts to melt almost uniformly, and the surface becomes smooth. F resin layer is easily formed.

On the other hand, when the fine particles are not included, as shown in FIG. 2A, there are many voids formed between the moderate particles in the powder layer. Therefore, when the powder layer is fired, as shown by the thick line in FIG. 2B, the surface of the powder layer starts melting along the shape of the moderate particles, and the shape of the moderate particles is changed. The F resin layer having the reflected unevenness on the surface is likely to be formed.
The F polymer having an adhesive group preferably used in the present invention tends to have a higher MFR than the F polymer having no adhesive group. Therefore, the F polymer having an adhesive group is difficult to flow even if it is melted during firing, and an uneven shape tends to remain on the surface of the F resin layer. In such a case, the effect of the present invention using the powder containing fine particles is particularly high.

In the present invention, Y / X is preferably 0.25 or less, more preferably 0.15 to 0.2. When Y / X is within the above range, the voids formed between the moderate particles in the powder layer are more reliably filled with the fine particles. As a result, an F resin layer having a smoother surface is formed. Note that Y / X is a value obtained by dividing Y by X.
Specifically, it is preferable that D10 is 4 μm or less and D50 is 15 to 60 μm. By adjusting the powders D10 and D50 within the above range, an F resin layer having a smooth and thin surface can be easily formed regardless of whether the F polymer has an adhesive group or not.

The D10 of the powder is more preferably 0.5 to 3.9 μm, further preferably 2 to 3.9 μm. When D10 is not more than the above upper limit value, an F resin layer having a smoother surface can be easily formed. When D10 is not more than the above lower limit value, the powder is less likely to adhere to the nozzle when the powder coating material containing the powder is applied, and the workability during the coating is improved.
The D50 of the powder is more preferably 17 to 50 μm, further preferably 20 to 40 μm. When D50 is equal to or higher than the above lower limit value, a thinner F resin layer can be easily formed. When D50 is not more than the above upper limit value, it is easy to form an F resin layer having a smoother surface.

The D100 of the powder is preferably 220 μm or less, more preferably 100 to 210 μm, and even more preferably 140 to 205 μm. When D100 is not more than the above upper limit value, the powder does not contain resin particles having a particle diameter too large with respect to the moderate particles (hereinafter, also referred to as “coarse particles”), so that the F resin layer has a smoother surface. Is easy to form. When D100 is equal to or higher than the above lower limit value, it is easy to form an F resin layer having a sufficient thickness.

Further, when the amount of resin particles having a particle size of 4 μm or less in the powder is A and the amount of resin particles having a particle size of 15 to 60 μm is B, the A / B is preferably 0.1 or more, and is 0. .2 or more is more preferable. The A / B is preferably 0.5 or less, more preferably 0.4 or less. If the A / B satisfies the above range, the voids formed between the moderate particles in the powder layer are filled with fine particles at a higher density. Note that A / B is a value obtained by dividing A by B.
The specific amount of the resin particles having a particle diameter of 4 μm or less contained in the powder is preferably 5 to 25% by volume, more preferably 10 to 20% by volume. If resin particles having a particle diameter of 4 μm or less are included in such an amount, it is easy to form an F resin layer having a smooth surface even when the powder contains coarse particles.

Such powders are classified by (i) a method of obtaining an F polymer by a solution polymerization method, a suspension polymerization method or an emulsion polymerization method, removing an organic solvent or an aqueous medium to obtain a powder, and then classifying the powder. ii) It can be produced by a method of melt-kneading an F polymer and other components if necessary, crushing the kneaded product, and classifying the pulverized product if necessary.
The powder can also be produced by mixing the first powder having D50 of X and the second powder having D50 having Y in a predetermined ratio. The first powder and the second powder can be produced by the method (i) or (ii) above.

The powders D10 and D50 can be adjusted according to the type of pulverization method and pulverization conditions.
Examples of the crushing method include a method using a crusher such as a rotor mill, a pin mill, a hammer mill, a freezing hammer mill, an edge runner mill, a screen mill, a vibration mill, a sand mill, an eddy mill, a ball mill, and a basket mill. Above all, a method using a rotor mill or a pin mill is preferable from the viewpoint that the powders D10 and D50 can be easily adjusted within the above range.
When the rotation speed of the crusher is low, D10 and D50 tend to be large. When the rotation speed of the crusher is high and the crushing time is long, D10 and D50 tend to be small.

The powder coating material of the present invention is a powder coating material containing the powder of the present invention.
In the method for producing a laminate of the present invention, a powder coating material containing the powder of the present invention is supplied onto a base material and fired to form an F resin layer. As a result, a laminate having a base material and an F resin layer provided on the base material and formed from the powder coating material can be obtained.
The powder coating material may contain components other than the powder of the present invention, if necessary. Other components include pigments, carbon fiber and graphite.
The amount of the powder of the present invention contained in the powder coating material is preferably 90% by mass or more, more preferably 95% by mass or more. The upper limit of the amount of the powder of the present invention contained in the powder coating material is 100% by mass.

Examples of the base material include household items such as frying pans, pots, and irons, and factory piping.
Examples of the material of the base material include metals such as stainless steel and iron, resins, glass, and ceramics.
Electrostatic coating is preferable as a method for supplying the powder coating material.

The powder coating is preferably fired by heating it to a temperature equal to or higher than the melting point of the F polymer. The specific firing temperature is preferably 350 to 380 ° C, more preferably 350 to 375 ° C, and even more preferably 350 to 370 ° C. When the firing temperature is at least the above lower limit value, it is easy to form an F resin layer having a smooth surface, and the adhesion between the F element resin layer and the base material is enhanced.
On the other hand, when the firing temperature is not more than the above upper limit value, the melting point of the F polymer in the present invention is 260 to 320 ° C., so that it is possible to prevent the generation of gas due to the thermal decomposition of the F polymer. Therefore, it is possible to suppress the occurrence of foaming and cracks in the F resin layer, and it is easy to obtain a laminated body having high safety and excellent appearance. In other words, when an F polymer having a melting point of 260 to 320 ° C. is used, the firing temperature cannot be extremely increased, and the powder layer must be fired at a relatively low temperature. Since the powder of the present invention contains fine particles, it is easy to obtain an F resin layer having a smooth surface even when fired at a relatively low temperature.

The firing time is preferably 1 to 20 minutes, more preferably 1 to 15 minutes. When the firing time is at least the above lower limit value, it is easy to form an F resin layer having a smooth surface. When the firing time is not more than the above upper limit value, it is easier to suppress the occurrence of foaming and cracks in the F resin layer.

In the present invention, the operation of supplying the powder coating material on the substrate and firing it may be repeated twice or more.
In this case, the firing temperature and firing time in each firing step may be different or the same. Further, in this case, the total firing time is preferably 3 to 60 minutes, more preferably 4 to 60 minutes, further preferably 5 to 45 minutes, and particularly preferably 10 to 30 minutes. When the total firing time is not more than the above upper limit value, it is easy to suppress the occurrence of foaming and cracks in the F resin layer. When the total firing time is at least the above lower limit value, it is easy to form an F resin layer having a smooth surface, and the adhesion between the F resin layer and the base material is further enhanced.

The thickness of the F resin layer to be formed is preferably 50 to 750 μm, more preferably 100 to 500 μm. When the thickness of the F resin layer is at least the above lower limit value, the productivity of the laminated body is improved. When the thickness of the F resin layer is not more than the above upper limit value, the chemical resistance of the F resin layer is high.

The peel strength between the F resin layer and the base material is preferably 14 N / cm or more, more preferably 15 to 100 N / cm, further preferably 16 to 90 N / cm, and particularly preferably 16 to 85 N / cm. When the peel strength between the F resin layer and the base material is at least the above lower limit value, it indicates that the adhesion between the F resin layer and the base material is high, and the F resin layer is difficult to peel off from the base material.

Although the method for producing the powder and the laminate of the present invention has been described above, the present invention is not limited to the configuration of the above-described embodiment.
For example, the powder of the present invention may be added to any other constitution in the constitution described above, or may be replaced with any constitution exhibiting the same function.
In addition, the method for producing a laminate of the present invention may additionally have any other arbitrary step in the configuration of the above embodiment, or may be replaced with an arbitrary step that produces the same action.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

1. 1. Production of raw material powder [Production example 1]
Using NAH, TFE and PPVE, a raw material powder (A1) made of the F polymer (1) was produced according to the procedure described in paragraph [0123] of International Publication No. 2016/017801.
The ratios (mol%) of NAH units, TFE units and PPVE units contained in the F polymer (1) were 0.1, 97.9 and 2.0 in this order. The melting point of the F polymer (1) was 300 ° C., the MFR was 17.6 g / 10 minutes, and the D50 of the raw material powder (A1) was 1554 μm.

[Manufacturing Example 2]
A raw material powder (A2) made of the F polymer (2) was obtained in the same manner as in Production Example 1 except that the chain transfer agent was changed to 0.5 kg of methanol.
The ratios (mol%) of NAH units, TFE units and PPVE units contained in the F polymer (2) were 0.1, 97.9 and 2.0 in this order. The melting point of the F polymer (2) was 300 ° C., the MFR was 25.0 g / 10 minutes, and the D50 of the raw material powder (A2) was 1570 μm.

[Manufacturing Example 3]
A raw material powder (A3) made of the F polymer (3) was obtained in the same manner as in Production Example 1 except that the chain transfer agent was changed to 0.35 kg of methanol.
The ratios (mol%) of NAH units, TFE units and PPVE units contained in the F polymer (3) were 0.1, 97.9 and 2.0 in this order. The melting point of the F polymer 3 was 300 ° C., the MFR was 8.2 g / 10 minutes, and the D50 of the raw material powder (A3) was 1490 μm.
The ratio of each unit contained in the F polymer was measured by the method described in International Publication No. 2016/017801.
The melting point was measured using a differential scanning calorimeter (DSC-7020) manufactured by Seiko Instruments Inc. The heating rate of the F polymer was 10 ° C./min.
MFR measures the mass (g) of F polymer flowing out from a nozzle having a diameter of 2 mm and a length of 8 mm in 10 minutes (unit time) under a load of 49 N at 372 ° C using a melt indexer manufactured by Techno Seven. I asked for it.
The raw material powder D50 was determined by the following procedure.
From top to bottom, 2.000 mesh sieve (opening 2.400 mm), 1.410 mesh sieve (opening 1.705 mm), 1.000 mesh sieve (opening 1.205 mm), 0.710 mesh sieve (opening 1.205 mm). Opening 0.855 mm), 0.500 mesh sieve (opening 0.605 mm), 0.250 mesh sieve (opening 0.375 mm), 0.149 mesh sieve (opening 0.100 mm), and a saucer were stacked.
The raw material powder was placed in the top sieve and sieved for 30 minutes with a shaker. The mass of the raw material powder remaining on each sieve is measured, the cumulative mass of passing mass for each opening value is shown in a graph, and the particle size at which the cumulative mass of passing mass is 50% is obtained, and the raw material powder is D50. did.
2. 2. Production of powders and laminates [Example 1]
First, the raw material powder (A1) was pulverized using a rotor mill (Rotor Speed Mill P-14 manufactured by Fritsch) under the condition of a rotation speed of 1700 rpm to obtain a pulverized powder.
Next, the pulverized powder was classified into powder (B1) using a circular vibrating sieve (manufactured by Seishin Enterprise Co., Ltd., KGO-1000 type, mesh opening 212 μm).
The powder (B1) has a D10 of 3.8 μm, a D50 of 22.2 μm, a D90 of 100.6 μm, and a D100 of 200.5 μm, a sparsely packed bulk density of 0.491 g / mL, and a densely packed bulk density of 0.491 g / mL. It was 0.646 g / mL.

First, a steel plate made of SUS304 having a length of 40 mm, a width of 150 mm, and a thickness of 2 mm was prepared.
Next, the surface of the steel sheet was sandblasted using 60 mesh alumina particles so that the surface roughness Ra was 5 to 10 μm.
Then, the surface of the steel sheet was cleaned with ethanol to prepare a base material.
After electrostatically coating the surface of the base material with a powder coating material made of powder (B1), the operation of firing at a firing temperature of 350 ° C. and a firing time of 4 minutes was repeated 10 times to obtain a laminate.
The thickness of the F resin layer formed on the base material was 314 μm.

[Example 2]
First, a raw material powder (A2) was pulverized using a pin mill (M-4 type manufactured by Seishin Enterprise Co., Ltd.) under the condition of a rotation speed of 5000 rpm to obtain a pulverized powder.
Next, the pulverized powder was classified into powder (B2) using a circular vibrating sieve (manufactured by Seishin Enterprise Co., Ltd., KGO-1000 type, mesh opening 212 μm).
The powder (B2) has a D10 of 3.6 μm, a D50 of 21.1 μm, a D90 of 99.4 μm, and a D100 of 181.9 μm, a sparsely packed bulk density of 0.524 g / mL, and a densely packed bulk density. It was 0.695 g / mL.
Next, the powder coating material made of powder (B2) is electrostatically coated on the surface of the base material prepared in the same manner as in Example 1, and then the operation of firing at a firing temperature of 350 ° C. and a firing time of 6 minutes is repeated twice. Obtained a laminate.
The thickness of the F resin layer formed on the base material was 330 μm.

[Example 3]
A powder (B3) was obtained in the same manner as in Example 2 except that the raw material powder (A3) was used instead of the raw material powder (A2).
The powder (B3) has a D10 of 3.9 μm, a D50 of 24.4 μm, a D90 of 78.2 μm, and a D100 of 169.9 μm, a sparsely packed bulk density of 0.525 g / mL, and a densely packed bulk density of 0.525 g / mL. It was 0.699 g / mL.
Next, the powder coating material made of powder (B3) is electrostatically coated on the surface of the base material prepared in the same manner as in Example 1, and then the operation of firing at a firing temperature of 350 ° C. and a firing time of 4 minutes is repeated 5 times. Further, after the powder coating was electrostatically coated, the operation of firing at a firing temperature of 350 ° C. and a firing time of 6 minutes was performed once to obtain a laminate.
The thickness of the F resin layer formed on the base material was 330 μm.

[Example 4]
A powder (B4) was obtained in the same manner as in Example 2 except that the rotation speed of the pin mill was changed to 2100 rpm and no classification was performed.
The powder (B4) has a D10 of 10.6 μm, a D50 of 94.4 μm, a D90 of 260.1 μm, and a D100 of 340.1 μm, a sparsely packed bulk density of 0.729 g / mL, and a densely packed bulk density of 0.729 g / mL. It was 0.835 g / mL.
Next, a laminate was obtained in the same manner as in Example 3 except that a powder coating material made of powder (B4) was used.
The thickness of the F resin layer formed on the base material was 330 μm.

[Example 5]
Powder (B5) was obtained in the same manner as in Example 2 except that the rotation speed of the pin mill was changed to 2100 rpm.
The powder (B5) has a D10 of 10.6 μm, a D50 of 82.1 μm, a D90 of 186.5 μm, and a D100 of 212.0 μm, a sparsely packed bulk density of 0.511 g / mL, and a densely packed bulk density. It was 0.672 g / mL.
Next, a laminate was obtained in the same manner as in Example 3 except that a powder coating material made of powder (B5) was used.
The thickness of the F resin layer formed on the base material was 330 μm.

[Example 6]
Powder (B6) was obtained in the same manner as in Example 2 except that the rotation speed of the pin mill was changed to 3000 rpm.
The powder (B6) has a D10 of 9.2 μm, a D50 of 56.9 μm, a D90 of 131.6 μm, and a D100 of 203.2 μm, and has a sparsely packed bulk density of 0.529 g / mL and a densely packed bulk density. It was 0.691 g / mL.
Next, a laminate was obtained in the same manner as in Example 3 except that a powder coating material made of powder (B6) was used.
The thickness of the F resin layer formed on the base material was 330 μm.

[Example 7 (Comparative example)]
A powder (B7) and a laminate were obtained in the same manner as in Example 2 except that the rotation speed of the pin mill was changed to 4000 rpm.
The powder (B7) has a D10 of 8.3 μm, a D50 of 25.5 μm, a D90 of 120.6 μm, and a D100 of 191.3 μm, a sparsely packed bulk density of 0.503 g / mL, and a densely packed bulk density of 0.503 g / mL. It was 0.657 g / mL.
The thickness of the F resin layer formed on the base material was 330 μm.

The particle size and amount of the resin particles constituting the powder, the sparsely packed bulk density and the densely packed bulk density were measured as follows.
(Measurement of particle size and amount of resin particles)
Using a laser diffraction / scattering type particle size distribution measuring device (LA-920 measuring device) manufactured by HORIBA, Ltd., the powder was dispersed in water, the particle size distribution was measured, and D10, D50, D90 and D100 were calculated.
Further, from the obtained graph of the particle size distribution, the amount of resin particles having a particle size of 4 μm or less and the amount of resin particles having a particle size of 15 to 60 μm were determined.
(Sparsely filled bulk density and densely packed bulk density)
The sparsely packed bulk density and the densely packed bulk density of the powder were measured using the methods described in [0117] and [0118] of International Publication No. 2016/017801, respectively.

3. 3. Measurement and evaluation 3-1. Peeling Strength First, cuts were made at intervals of 10 mm from the surface side of the F resin layer of the laminate obtained in each example using a cutter knife.
Next, a part of the F resin layer was peeled off and fixed to the chuck of the tensile tester.
Then, the peel strength (N / cm) when the F resin layer was peeled from the substrate was measured at a tensile speed of 50 mm / min and 90 °.

3-2. Appearance Evaluation In each example, 100 laminated bodies were prepared, the surface of the F resin layer of each laminated body was visually confirmed, and the appearance was evaluated according to the following evaluation criteria.
<Evaluation criteria>
⊚: No unevenness was observed on the surface of the F resin layer in any of the laminated bodies.
◯: Unevenness was observed on the surface of the F resin layer in the laminated body of 5 or less.
Δ: Unevenness was observed on the surface of the F resin layer in the 6 to 10 laminated bodies.
X: Unevenness was observed on the surface of the F resin layer in the laminated body of more than 10 pieces.
In addition to the above results, Table 1 shows the powder production conditions, the particle diameters (D10, D50, D90, D100) and the amount, and the laminate production conditions.

As shown in Table 1, in Examples 1 to 6 in which the relationship between D10 and D50 was within the range specified in the present invention, the adhesion between the base material and the F resin layer was excellent.
In Examples 1 to 3 using a powder having a small D50, an F resin layer having a smooth surface is formed, whereas in Examples 4 to 6 using a powder having a large D50, unevenness occurs on the surface of the F resin layer. It showed a tendency.
In Example 7 using a powder in which the relationship between D10 and D50 deviates from the range specified in the present invention, unevenness was observed on the surface of the F resin layer. In addition, the adhesion between the base material and the F resin layer tended to decrease.

The powder of the present invention is suitable for powder coating materials used for powder coating, and is particularly suitable for powder coating materials that form a thick fluororesin layer having a smooth surface.
The entire contents of the specification, claims, abstract and drawings of Japanese Patent Application No. 2017-235350 filed on December 07, 2017 are cited here and incorporated as disclosure of the specification of the present invention. It is a thing.

Claims (12)

A powder composed of resin particles containing a fluoropolymer having a unit based on tetrafluoroethylene and having a melting point of 260 to 320 ° C.
A powder having a Y / X of 0.3 or less, where X is a volume-based cumulative 50% diameter and Y is a volume-based cumulative 10% diameter. The powder according to claim 1, wherein the volume-based cumulative 10% diameter is 4 μm or less and the volume-based cumulative 50% diameter is 15 to 60 μm. When the amount of resin particles having a particle size of 4 μm or less contained in the powder is A and the amount of resin particles having a particle size of 15 to 60 μm is B, A / B is 0.1 or more. Item 2. The powder according to Item 2. The powder according to claim 2 or 3, wherein the amount of the resin particles having a particle diameter of 4 μm or less contained in the powder is 5 to 25% by volume. The powder according to any one of claims 1 to 4, wherein the volume-based cumulative 100% diameter is 220 μm or less. The powder according to any one of claims 1 to 5, wherein the fluoropolymer has at least one functional group selected from the group consisting of a carbonyl group-containing group, a hydroxy group, an epoxy group and an isocyanate group. The powder according to claim 6, wherein the fluoropolymer has a unit based on the tetrafluoroethylene and a unit having the functional group. A powder coating material containing the powder according to any one of claims 1 to 7. The powder coating material according to claim 8, wherein the amount of the powder contained in the powder coating material is 90 to 100% by mass. A method for producing a laminate having a base material and a fluororesin layer provided on the base material and formed from the powder according to any one of claims 1 to 7.
A method for producing a laminate, wherein a powder coating material containing the powder is supplied onto the base material and fired to obtain the fluororesin layer. The production method according to claim 10, wherein the powder coating material is fired by heating it above the melting point of the fluoropolymer. The production method according to claim 10 or 11, wherein the fluororesin layer has a thickness of 50 to 750 μm.

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